Words and designs are frequently printed onto clothing, other textile materials, and other objects. Common means of applying such designs to objects include the use of silk screens, and mechanically bonded thermal transfers.
The use of computer technology allows substantially instantaneous printing of images. For example, video cameras or scanning may be used to capture an image and input the image into a computer. The image may then be printed from the computer by any suitable printing means, including mechanical thermal printers, ink jet printers and laser printers. These printers will print in multiple colors.
Color electrographic devices, such as laser printers and photocopiers, are in common use. These devices use combinations of cyan, yellow and magenta inks or dyes to produce multi-color images. These devices use inks in the form of dry toners or developers. These devices incorporate means for fusing the printed ink or dye to the substrate, which is usually paper. The fusing means incorporates heat, or heat and pressure.
Sublimation inks have been used with laser printers and copiers to produce color images on the receptor sheet printed by the printer or copier, whereby sublimation or activation of the ink or dye occurs at the time of printing or fusing of the image onto the receptor by the printer or copier. The sublimation dyes used are low energy, that is, they require low amounts of heat to activate, so that activation is achieved during the very short image fixing time provided by conventional laser printers and copiers. The receptor must be coated, or otherwise include, a polymer or polyester component. Toners comprising sublimable dyes and a polyester core which are encapsulated in a waxy compound to improve storage stability are disclosed in Japanese application serial number 85-171830.
Sublimation inks have been printed by electrographic devices in the prior art in monochromatic form, without activating the inks as they are printed onto the substrate. Multiple colors are printed by such processes by multiple apllications of monochromatic process. These processes are not full process color which can be used with color laser printers, color copiers or other full color electrographic process. The prior art has encountered problems related to dye layer build up, registration, and color contamination in trying to print sublimation inks in a non-activated form from known color electrographic devices.
Heat activated transfer inks, such as sublimation inks, change to a gas upon the apllication of heat, and have a high affinity for polyester at the activation temperature and a limited affinity for most other materials. Once the gassification bonding takes place, the ink is permanently printed, and is highly resistant to change or fading caused by environmental exposure, such as to light, or exposure to certain common chemical processes, such as cleaners or laundry products.
Hale, U.S. Pat. Nos. 5,246,518, 5,248,363 and 5,302,223, disclose the use of thermal printers to produce an image on a medium or transfer sheet wherein the image is comprised of sublimation or other heat activated inks. The method described in Hale does not activate the ink during the printing of the medium or transfer sheet.
The process of printing heat sensitive or activated inks such as sublimation inks by means of a laser printer is similar to the process described in Hale, U.S. Pat. Nos. 5,246,518, 5,248,363 and 5,302,223. The use of heat by electrographic devices such as laser printers and photocopiers presents the problem recognized in the Hale patents of printing heat activated inks in a non activated form by means of such devicess. Laser printers and photocopiers in common use employ relatively high temperature fuser devices to thermally fuse or bind the ink to the substrate, since these devices anticipate that the image will be permanently bonded to the substrate which is printed by the device, and do not anticipate a subsequent thermal transfer of the printed image from the substrate.